This car was unusual for France – production of luxury cars was heavily restricted in the country by post-World War II puissance fiscale horsepower tax, so France had not had a production vehicle in this market sector since before World War II.

[5] Citroën's flagship vehicle competed with high-performance GTs of the time from other nations and manufacturers, such as Jaguar, Ferrari, Aston Martin, Alfa Romeo, Mercedes-Benz, Porsche and Maserati's Merak.

Some owners have fitted the similar sized 220 PS (162 kW) Maserati Merak SS engine, which does improve the driving experience considerably.

The SM was Citroën's means of demonstrating just how much power and performance could be accommodated in a front-wheel drive design.

This new type of variable assist power steering was later fitted to the Citroën CX in large numbers and its basic principle has since spread throughout the vehicle production.

[9] When the SM was cast as a TV series regular on The Protectors (1972), the lead actress refused to drive it, because of the familiarization required from the steering.

This feature allows the front wheels to run near-zero caster, and means that there is no camber change as lock is applied, and also ensures that the maximum amount of tyre area is in contact with the road at all times.

The bonnet is aircraft grade aluminum, while the external bright work is stainless steel, rather than 'cheaper' chrome (except for "plastichrome" "SM" trim at the rear base of the rain gutter).

It was an example of the car as a symbol of optimism and progressive technology, similar to the SM's contemporary, the Concorde aircraft.

Competitors included the Cadillac Eldorado, Lincoln Mark IV and Ford Thunderbird alongside Italian, British, and German imports.

[29] The unique design of the SM made quite a splash and won the Motor Trend magazine's Car of the Year award in 1972, unheard of for a non-US vehicle at the time.

[29] Despite initial success, U.S. sales ceased suddenly when Citroën did not receive an expected exemption for the 1974 model year 5 mph (8.0 km/h) bumper regulation imposed by the NHTSA.

[29][34] The 1974 SMs built for the U.S. market (134 cars), could not be supplied to Americans due to the effective date of the bumper regulation, so were sold in Japan instead.

It was a very compact and innovative design that allowed the use of just one pattern for the cylinder heads and an intermediate shaft extended out to drive the auxiliaries.

[36] The size of the 2.7 L engine was limited by French puissance fiscale taxation, which made large displacement vehicles too expensive to sell in any quantity in France.

Peugeot quickly decided to stop building the SM, as production had dropped to 294 cars in 1974 and 115 units the final year.

[40][29] While the oil shock certainly affected sales, many far more profligate cars were introduced at the same time the SM ceased production, including the hydropneumatically suspended Mercedes-Benz 450SEL 6.9.

[41] However, the U.S. National Highway Traffic Safety Administration (NHTSA) imposed new automotive design regulations in 1974, effectively banning the Citroën from the U.S.

[29] The Quai André-Citroën factory on the banks of the Seine River in Paris closed in 1974, necessitating new manufacturing facilities for both the DS and the SM.

The successful Citroën CX carried forward most of the SM's dynamic qualities, including the trendsetting speed sensitive power steering.

French Presidents from Georges Pompidou to Jacques Chirac enjoyed touring Paris in the two 4-door convertible Citroën SM présidentielle models, sharing them with such notables as Pope John Paul II and visiting heads of state.

[46] These manual transmission cars have special low gearing and additional cooling suitable for parade use, allowing them to travel at a speed of 6–7 km/h (3.7–4.3 mph).

[47] They also feature a small, rearward-facing dropdown seat for the use of a translator or secretary, and an electrically powered top with hydraulic actuators.

[49] Unlike the DS, the factory never authorized a convertible model, as Citroën felt the roof was integral to the structure of the SM.

Just before the SM's demise, Citroën produced several short-wheelbase racing versions with squared-off rear sections and highly tuned engines – known as the "breadvan" model.

In the UK, three official RHD prototypes were constructed by Middleton Motors, a Citroën dealer in Hertfordshire, England.

The SM Club of France created an exact replica of this car using the actual engine from the original and displayed it at the Rétromobile 2010 show.

The Maserati Quattroporte II was a Maserati-badged, four-door variant of the SM with an angular body and lengthened floorpan.

[11] General Secretary of the Communist Party of the USSR Leonid Brezhnev,[54] Rolling Stones bassist Bill Wyman,[55] Adam Clayton of the rock group U2,[56] and Emperor Haile Selassie I of Ethiopia each drove SMs, while Ugandan dictator Idi Amin had seven of them.

Actors Lorne Greene and Lee Majors, composer John Williams, author Graham Greene, and former Mauritian QC and Politician Sir Gaetan Duval (1930–1996), football player Johan Cruijff, Rolling Stones drummer Charlie Watts, Cheech & Chong's Cheech Marin and Thomas Chong,[58] motorcycle racer Mike Hailwood,[59] composer John Barry, and musician Carlos Santana, all owned SMs as well.